THE DEPENDENCE OF SECONDARY SEX- 

 CHARACTERS UPON TESTICULAR HORMONES 

 IN LEBISTES RETICULATUS. 



L. J. BLACKER, 

 BIOLOGICAL LABORATORY OF THE ZOOLOGICAL GARDEN OF Moscow, RUSSIA. 



I. INTRODUCTION. 



The problem of sex as a chapter in the mechanics of develop- 

 ment has not been investigated until lately. A number of 

 authors whose investigations were performed on different animals 

 have proven that those sex-characters which are generally called 

 secondary sex-characters depend in their development, on 

 hormones produced in the sex glands. After castration these 

 characters will disappear. Proof to this effect has been produced 

 by Steinach, Sand and Lipschiitz in mammals; Pezard, Goodale 

 and Zawadawsky in birds; Harms, Meisenhaimer, Witschi, 

 Bresca and others in amphibians. 



The dependence of secondary sex-characters in fishes was not 

 at all investigated until quite recently. The reason for this may 

 be found in the fact that those species which are endowed with 

 permanent dimorphism, the exotic inhabitants of the aquaria, 

 are distinguished by a very scant size and want of stability and 

 therefore, are almost inaccessible for operative intervention. 



As to seasonal dimorphism we find in the works of Courrier (2) 

 and Von Oordt (5, 6, and 7) on the stickleback (Gasterosteus 

 pungitius and G. aculeatus} indirect indications of its dependence 

 on the hormones of the testis. 



A direct experiment was carried out by St. Kopec (4) who 

 succeeded in castrating Phoxinus Ixvis males and females and 

 keeping them alive for three weeks after operation. During 

 this time said fish failed to exhibit nuptial colors at the usual time. 



The hybridological analysis of the sex-characters in fishes was 

 carried out by Aida (i) on Haplochihis latipes and by Winge (8 

 and 9) on Lebistes reticulatus. Both authors came to the con- 

 clusion that the color characters of the male depend on the genes 

 located in the sex-chromosome, especially in the Y-chromosome. 



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